Haskell report 5.4 says that instance visibility is transitively kept amongst module imports.

So, if A imports B, B imports C, and inside C.hs I have instance Eq C, it is enough to import A in Main.hs to have the Eq C instance visible. It is not required to import C directly.

When I use the import chain, the compiler works correctly, but ghci :info Eq doesn't report C as an instance, only if I import C directly.

This behavior is misleading, because if someone is not familiar with the specification, may believe after trying with :info that the instance is not transitively visible.

I attached a test for this issue, after unpacking you can use demo.sh to demonstrate the issue.